Patent Document 1 discloses an airbag which includes regulating means for regulating the outflow of gas through a vent hole. The regulating means includes a squeezing member which can squeeze the vent hole, and a connecting member which is provided for connecting the squeezing member and a surface of the airbag which faces an occupant. When the airbag is inflated, the squeezing member is pulled by way of the connecting member so that the vent hole is closed. However, when the occupant comes into contact with the inflated airbag so that the surface of the airbag which faces the occupant retracts, the squeezing member is loosened so that the vent hole is opened.
As another prior art relating to the present invention, there is Patent Document 2.